This very useful guide, and the recipe below, is taken from Modern Baker: A New Way To Bake by Melissa Sharp with Lindsay Stark (Ebury Press, RRP £26).

A sourdough starter is how we cultivate wild yeast in a form that can be used for baking and has been done for thousands of years. The easiest way to make one is simply to combine flour and warm water and let the mixture sit for several days. In theory, you will only need to do this once in your life and it is unique to you. The start is the magic, the genius, at the heart of everything we do and everything in this book. It’s an ancient technology, discovered by accident and passed from generation to generation. It forms the basis of transformation foods with unbelievable powers of preservations and flavour.

A lot of people are intimidated by the idea of making and keeping a starter, but it really doesn’t need to be daunting and is in fact something a child could do, getting a starter going takes 2 minutes a day, over 5 days. It’s really not that much effort at all. If you use it on a regular basis, maintaining it just becomes part of your bread and baking routine, and if you do not use it as regularly, or you’re going on holiday and are worried about leaving it for a while, don’t be. It can cope!

Keep your start in the fridge unless you are using it every day. Bring it out to top it up, then return it when you have finished using it in your recipes. It will be fine there even for a few months without being used. It may separate in the meantime, but don’t panic, just mix it back together. To get it going again you want to really overwhelm it with food. So throw half of it away and add 100g flour and 100g warm water. Leave it overnight at room temperature and the next day it should be active again, i.e. bubbling away. It really is that straightforward.

At this stage you could use it, but we would actually recommend throwing half of it away again and topping it up with however much you need for your recipe. We find that by taking that one extra day with a rejuvenated starter you get a much more active starter, resulting in a better flavour and rise in your bread.

A sourdough start is also known as a levain, and sometimes a mother (because it keeps producing babies).

In the bakery, we have three bread starters: wheat, rye and brown rice for gluten-free baking. For our basic sourdough we use the wheat starter. This has an almost cheesy smell to it and a slightly more mellow flavour than the rye starter.

How to use your starter in bakingNow you have your active starter you’re ready to start sourdough baking. The first thing to remember if that to make sourdough recipe you will need to build up your active starter (using all of it) the day before your bake. How to do this is detailed in each recipe under the heading on Day 1.

Having built your starter up, you will need to use most of it for the recipe (in the recipe we refer to it as the Recipe starter). What you don’t use, you retain as your ongoing active starter for your next recipe – you don’t want to have start from scratch each time! This all sounds more confusing that it really is.

Trouble-shootingIf the starter isn’t obviously bubbling, keep repeating Day 2 until it starts to. Quite a few factors can affect how long it takes a starter to activate, temperature being one of the main ones. If you begin your starter in cold conditions it may take longer to get going. Also, the general environment can have an impact. In the bakery, as we are making bready every day, there is so much yeast in the atmosphere that we find starters can take just a few days to get going, whereas if a kitchen is more sterile, it’s likely to take much longer.

Ingredients

Method

1 Day 1: Mix together the flour and the water in a container with a lid. We recommend missing with your hands rather than a spoon. As disgusting as it might sound, we all have naturally occurring yeasts on our hands, so this can give your starter a real boost.

Leave the mixture overnight at room temperature. Cover it with the lid but do not make it airtight. A screw-top jar with the lid partly done up is perfect. You want the yeasts in the air to get in, but you also want to stop the mixture drying out.

2 Day 2: Take the wheat starter you made on Day 1, and 1 tsp strong white flour and 1 tsp water, at hand warm temp (32-37 degrees). Throw away half of the mixture from Day 1. This is because you want to almost overwhelm the bacteria/yeast in the starter with food, by adding more flour than the weight of the original mixture. You could do this by adding more flour and warm water and not throwing any away, but you would very quickly end up with an excessively large amount of starter.

Stir the flour and water into the remaining mix and leave again at room temperature overnight.

3 On days 3 and 4, repeat the step above.

4 Day 5: By now you should notice your starter has bubbles in it. This means it is ready! Don’t worry if it smells acidic or cheesy, this is completely normal and each starter will create its ow unique fragrance. Now you have your own living, bubbling jar of healthy microbes that you’ll be using for years to come.